MR findings of secondary hemochromatosis: transfusional vs erythropoietic

OBJECTIVE

The aim of this study was to demonstrate the MR characteristics of secondary hemochromatosis (transfusional versus erythropoietic).

MATERIALS AND METHODS

Magnetic resonance images of five patients with transfusional (n = 3) or erythropoietic (n = 2) hemochromatosis were reviewed.

RESULTS

The liver of all patients had low signal intensity in all pulse sequences. The spleen had low signal intensity in all patients with transfusional iron overload, but normal signal intensity in erythropoietic hemochromatosis, which had similar MR findings to idiopathic hemochromatosis. However, the pancreas had variable signal intensity.

CONCLUSION

On MRI the signal intensity of the spleen may allow distinction between transfusional and erythropoietic hemochromatosis.

Interventional management of benign obstruction of the hepatic inferior vena cava

PURPOSE

The effectiveness of interventional treatment of benign obstruction of the hepatic segment of the inferior vena cava (IVC) was evaluated in a retrospective analysis.

PATIENTS AND METHODS

Among 21 patients, 14 obstructions were membranous (type 1) and seven were segmental (type 2). IVC thrombosis was found proximal to the obstruction in five patients. Percutaneous transluminal angioplasty (PTA) was attempted in patients with type 1 obstruction with use of a double balloon technique in most cases (12 of 14 cases). For six of the seven patients with type 2 obstruction, metallic stent placement and PTA were performed with or without urokinase thrombolysis or percutaneous aspiration thrombectomy. Follow-up evaluation was performed with vena cavography, pressure measurement, and liver function tests.

RESULTS

The overall initial success rate was 95% (20 of 21 cases). The mean pressure gradient across the obstruction decreased significantly from 14.1 mm Hg +/- 4.1 to 4.2 mm Hg +/- 3.7 (P < .01) in 10 patients with type 1 obstruction and from 15.7 mm Hg +/- 3.1 to 6.0 mm Hg +/- 3.3 (P < .05) in six patients with type 2 obstructions. During the follow-up period from 6 months to 6 years, patency was maintained in nine of 10 patients with type 1 obstruction. Among the seven patients with type 2 obstruction, restenosis developed in two. Intimal thickening inside the metallic stent was found on the follow-up vena cavogram for all six patients who underwent stent placement.

CONCLUSION

For the interventional treatment of benign obstruction of the hepatic IVC, PTA with the double balloon technique is effective for the membranous type (type 1), and combined interventions including PTA, thrombolysis with urokinase, percutaneous aspiration thrombectomy, and metallic stent placements seem effective in the treatment of the segmental type (type 2). The long-term effects, including intimal thickening in cases involving the use of metallic stents, warrant further investigation.

Colitis in Behçet's disease: characteristics on double-contrast barium enema examination in 20 patients

We performed a retrospective review of double-contrast barium enema examinations of 20 patients with clinically proven Behçet's colitis. Main lesion was ovoid or geographic ulcers with a mean diameter of 2.7 cm. The number of ulcers was single in 15 cases and multiple in five. On six resected specimens, ulcers involved submucosa in three, muscle layer in one, and serosa in two cases with an undermining tendency and transmural inflammation. Aphthous ulcers were present in three cases. Neither perforation nor fistula was demonstrated. In all 20 patients, the ulcer was localized in the ileocecal area, with extension to the ascending colon in seven. Skip lesions were observed in the transverse colon and descending colon in three cases. Destruction of surrounding mucosa resulted in cecal contraction in 19 cases, widening of the ileocecal valve in 19, and fold thickening in the terminal ileum in 12. Six cases (30%) manifested as ileocecal mass accompanied by ulcer, fold thickening, and adjacent mucosal deformity. The appendix was visualized in only three (20%) of the 15 patients with no history of appendectomy. On follow-up study of 15 cases, the ulcers disappeared or decreased in size in 13 cases (86%) and the mucosal deformity was not improved in all cases. On the basis of our results, we believe that the characteristic findings of colitis in Behçet's disease in barium enema examination are ovoid or geographic, relatively large, and deep ulcerations with persistent surrounding deformity which tend to localize in the ileocecal area.

Combined hepatocellular and cholangiocarcinoma of the liver: sonography, CT, angiography, and iodized-oil CT with pathologic correlation

To evaluate the characteristics of combined hepatocellular and cholangiocarcinoma of the liver by imaging techniques, six patients (five male and one female), aged 46-60 years, with proved combined tumors were selected for this study from the review of 500 resected specimens of liver tumors. Images obtained from sonography, computed tomography (CT), angiography, and CT after intraarterial injection of iodized oil (iodized-oil CT) were retrospectively reviewed and correlated with the appearance of pathologic specimens. Sonographic findings were round or ovoid hypoechoic masses with central hyperechoic area (target appearance) in all patients. On CT scans, tumors were relatively well-defined low-and/or iso-attenuation masses in all patients. Angiography showed hypovascular masses in five patients. In one patient, the tumor appeared as a hypovascular mass with a central hypervascular area. On iodized-oil CT scans, all patients showed partial retention of iodized oil in tumors. Echogenicity in tumors at sonography or attenuation in tumors at CT could not be correlated with histologic difference in tumors at pathologic specimens. However, the hypervascular area at angiography and the compact retention areas of iodized oil at iodized-oil CT corresponded to portions of hepatocellular carcinoma within the combined tumor. On the basis of our results, imaging features, including target appearance at sonography, hypovascular mass with central hypervascular portions at angiography, and partial retention of iodized oil in tumors at iodized-oil CT, might be helpful in making accurate diagnosis of these rare tumors.

Perforation of the gastroduodenal artery induced by steerable guidewires in two cases: treatment of hemorrhage by embolization

We encountered 2 cases of guidewire-induced perforation of the gastroduodenal artery after using a hydrophil-coated guidewire. The guidewire penetrated a small side branch of the normal gastroduodenal artery in 1 patient and the weakened gastroduodenal artery due to pancreatic pseudocyst in the other patient. Both complications resulted in serious hemorrhage and were successfully managed by transcatheter embolization using steel coils. In an era of widespread use of hydrophil-coated guidewires for superselective catheterization, it is important to appreciate the possibility of this potentially serious complication.

Hematogeneous pulmonary metastasis. An experimental study using VX-2 carcinoma in rabbits

The purpose of this study was to develop an experimental model of pulmonary metastases using VX-2 tumor, and to describe sequential radiologic and pathologic findings with special attention to the interstitial changes around the metastatic nodules. Through ear veins of 25 rabbits, VX-2 tumor cell suspension was injected with 0.8-mm scalp needles. Chest radiographs were taken every other day after tumor injection. The rabbits were sacrificed at scheduled times from 3 to 30 days after tumor injection. The inflated and fixed lungs were examined with visual inspection, low-kV radiography, high resolution CT (HRCT), microradiography of the sliced lung and with histopathologic studies. Hematogeneous pulmonary metastases occurred in 24 of 25 rabbits. In addition to the metastatic nodules, perinodular and peribronchovascular infiltrations were seen on low-kV radiography, HRCT, microradiography and histologic studies.

Embryonic expression of Fgf-6 is restricted to the skeletal muscle lineage

As part of an ongoing examination of the functions of the fibroblast growth factor (FGF) gene family in mammalian development, we have carried out an RNA in situ hybridization analysis of the Fgf-6 gene in the mouse embryo. In contrast to what has been found for three other members of the FGF gene family, no Fgf-6 RNA was detected in mouse embryos at E6.5 through E8.5. Fgf-6 RNA was first detected in embryos at E9.5 and was localized exclusively in the myotomal compartment of the somite. Similar results were obtained with embryos at E10.5 and E11.5. At E12.5, expression was still detected in the myotome, and also in the region containing the developing muscles of the body wall. By E14.5, Fgf-6 RNA was found in the majority of skeletal muscles in the fetus. These results are discussed in comparison with what is known about the expression patterns of the genes encoding other FGF family members, as well as their high-affinity receptors.

Preoperative staging of uterine cervical carcinoma: comparison of CT and MRI in 99 patients

OBJECTIVE

The aim of this study was to compare CT and MRI at 0.5 T in the preoperative staging of uterine cervical cancer in a large series of patients.

MATERIALS AND METHODS

Ninety-nine patients with uterine cervical carcinoma underwent CT, MRI, and surgical exploration.

RESULTS

Both CT and MR findings were compared using surgical-pathologic findings as gold standards. Magnetic resonance imaging was superior to CT in tumor detection (sensitivity 75 vs. 51%, p < 0.005), in parametrial evaluation (accuracy 87 vs. 80%, p < 0.005), in overall tumor staging (accuracy 77 vs. 69%, p < 0.025), and in pelvic lymph node evaluation (accuracy 88 vs. 83%, p < 0.01). Magnetic resonance imaging had an accuracy of 76% in assessment of the thickness of cervical stromal invasion.

CONCLUSION

Magnetic resonance imaging was superior to CT in preoperative staging of uterine cervical carcinoma and MRI should be used instead of CT for preoperative staging of this disease.

Radiological findings of human fascioliasis

Fasciola hepatica is a trematode of herbivorous mammals. Humans are accidentally infected by the ingestion of water or raw aquatic vegetables contaminated with the metacercaria. Radiological findings of six patients with fascioliasis (five hepatic fascioliasis, one biliary fascioliasis) were analyzed. The diagnosis was based on serological testing and/or histopathologic findings of eosinophilic abscess in five patients and identification of the adult worm in one patient. The characteristic radiological features of hepatic fascioliasis were (1) cluster of microabscesses arranged in tract-like fashion (burrow tract), (2) subcapsular location of the hepatic lesions, and (3) very slow evolution of the lesion on follow-up examinations. In biliary fascioliasis, there were multiple conglomerated filling defects in the common bile duct. The authors believe that the demonstration of these features, together with peripheral eosinophilia or eosinophilic aspirate from the hepatic lesion, is very helpful in making the correct diagnosis.

Pulmonary oil embolism after transcatheter oily chemoembolization of hepatocellular carcinoma

The medical records of 336 patients with hepatocellular carcinoma who underwent transcatheter oily chemoembolization (TOCE) performed via the hepatic artery were retrospectively reviewed to ascertain the occurrence of symptomatic pulmonary oil embolism. In 14 patients, more than 20 mL of iodized oil was administered. In six of these 14 patients, respiratory symptoms of cough, hemoptysis, and dyspnea developed 2-5 days after TOCE, and their chest radiographs showed diffuse bilateral pulmonary parenchymal infiltrate. Their arterial partial pressure of oxygen while they breathed room air ranged from 39 to 60 mm Hg during maximum hypoxemia. The symptoms, arterial hypoxemia, and chest radiographic abnormalities completely cleared 10-28 days after TOCE in the five patients who survived. One patient died 10 days after TOCE because of respiratory arrest with a progression of pulmonary infiltrate. Although histopathologic proof is lacking, it is concluded that massive pulmonary embolization of iodized oil was the primary cause of the clinical and radiographic manifestations in these six patients.

Superselective transcatheter arterial embolization with ethanol and iodized oil for hepatocellular carcinoma

PURPOSE

The effectiveness of superselective transcatheter arterial embolization with a mixture of ethanol and iodized oil was evaluated for hepatocellular carcinoma.

PATIENTS AND METHODS

The procedure was attempted in 14 male patients with hepatocellular carcinoma. The tumor was a single small (2-5 cm in diameter) hypervascular nodule in all patients, except in one patient with two nodules. Superselective catheterization was performed with use of coaxial technique into the third-order branch of the feeding hepatic artery. Under fluoroscopy, 1-4 mL of 75% ethanol mixed with iodized oil was infused.

RESULTS

Complete segmental or subsegmental devascularization of the feeding arteries and tumor vascularities occurred in all patients. Follow-up CT or angiography after 9-37 months revealed decrease of tumor in six of nine nonsurgical cases. Subsequent segmentectomy or tumorectomy in five patients revealed total or near-total necrosis of the tumor and thickening of capsules, explaining the halo seen around the tumor on CT scans and the relatively intact surrounding parenchyma seen microscopically.

CONCLUSION

Superselective transcatheter arterial embolization with ethanol and iodized oil is a safe method for treatment of small nodular hepatocellular carcinoma with a prominent feeding artery.

Piezoelectric lithotripsy of radiopaque gallstones: results and six-month follow-up

Sixty-eight patients with radiopaque gallbladder stones (38 with a single stone, 30 with multiple stones) were treated with piezoelectric extracorporeal shock wave lithotripsy (ESWL) and results were compared with those of 69 patients with radiolucent stones (28 with a single stone, 41 with multiple stones). Stones were fragmented to 4 mm or less in 76.8% after 41,466 +/- 36,504 shock waves in the radiolucent stone group and 77.9% after 54,686 +/- 51,024 shock waves in the radiopaque stone group (p = 0.876 and 0.130, respectively). In 137 patients, ten patients were lost to follow-up. Average period of follow-up was 220 +/- 198 days. Six-month clearance rate of the radiolucent stone group was 43.5% and that of the radiopaque stone group was 16.4% (p less than 0.05) Figure 1. Six-month clearance rate of patients with single stones smaller than 2 cm was also significantly higher in the radiolucent stone group than in the radiopaque stone group (69.5% vs 18.6%; p less than 0.01). However, in patients with multiple stones, the presence of calcification did not affect rates of successful fragmentation or 6-month clearance. There was no statistically significant difference in incidence of complications between the radiolucent and radiopaque stone groups. Although the number of cases are small and the follow-up period is short, our results of ESWL on radiopaque gallstones are so far not satisfactory in terms of stone clearance. Strict patient selection is needed unless there is an improvement in the lithotripsy procedure or post-lithotripsy management.

Postoperative recurrence of hepatocellular carcinoma: results of transcatheter arterial chemoembolization

A retrospective analysis was made of the effect of transcatheter arterial chemoembolization (TACE) in 87 patients with recurrent hepatocellular carcinoma (HCC). In contrast to the predominantly single nodular HCC (60.2%) on preoperative angiography, recurrent HCC showed a multinodular pattern in 54.2%. Preoperative TACE had significantly prolonged the interval between surgery and recurrence. One- and 2-year survival rates after TACE of the 87 recurrent HCCs were 74.7% and 55.%, respectively, which were not significantly different from those of a control group of 206 patients with HCC in Child's class A, who were treated with TACE only. We believe that TACE is an effective measure in the management of preoperative and recurrent HCC.

Tuberculous stricture of the urinary tract: antegrade balloon dilation and ureteral stenting

In eight patients with tuberculous strictures of the urinary tract, antegrade balloon dilation and ureteral stenting was attempted. In six patients, antegrade balloon dilation was successfully performed; however, the procedure was aborted in the remaining two patients due to the failure in passing a guidewire through the stenotic lesions. In six patients in whom balloon dilation and ureteral stenting were performed, a total of nine stenotic lesions were dilated. Those were four ureteric lesions, two lesions of ureteropelvic junctions, two lesions of ureterovesical junctions, and a lesion of calyceal infundibulum. In all six patients in whom balloon dilation and ureteral stenting was successfully accomplished, intravenous urograms obtained 9-31 months after the procedure showed improvements both in contrast media excretion and in prestenotic dilatation. Antegrade balloon dilation of the urinary tract combined with ureteral stenting was an effective technique for the management of stenoses secondary to tuberculosis of the urinary tract.

Left paracardiac mass caused by dilated pericardiacophrenic vein: report of four cases

OBJECTIVE

The pericardiacophrenic vein is a possible route of collateral circulation when either the superior or the inferior vena cava is obstructed. When the vein is dilated, it can cause an abnormal appearance on chest radiographs. We describe four such patients.

MATERIALS AND METHODS

We studied four patients who had abnormalities on conventional chest radiographs due to a grossly dilated pericardiacophrenic vein, confirmed by means of venacavography, CT, or MR imaging. We analyzed the cause of the dilatation and the radiologic findings associated with the dilated pericardiacophrenic vein.

RESULTS

The cause of the dilated pericardiacophrenic vein was the membranous obstruction of the inferior vena cava in all four patients. Chest radiographs revealed an undulating vascular shadow (in two cases) or a shadow of several masses (in one case) along the left border of the heart or a poorly defined haziness mimicking a pulmonary parenchymal infiltrate (in one case). A direct communication between the left hepatic vein and the left inferior phrenic vein was seen near their insertion into the inferior vena cava in three cases. Hepatic venous outflow and some of the systemic venous return were directed to this left inferior phrenic-pericardiacophrenic route.

CONCLUSION

When obstruction of the inferior vena cava is clinically suspected and the chest radiograph shows abnormalities at the left paracardiac area, a dilated pericardiacophrenic vein due to obstruction in the suprahepatic portion of the inferior vena cava, most likely a membrane, should be considered in the differential diagnosis.

Calcified gastric carcinoma: CT findings

The computed tomographic (CT) findings of 13 cases of calcified gastric carcinoma were analyzed retrospectively. Eleven cases were confirmed as a mucinous adenocarcinoma by surgery (three cases), or endoscopic biopsy (eight cases). Two cases were diagnosed as adenocarcinoma by endoscopic biopsy. In all cases the calcifications were of the punctate or miliary shape and the size varied from 1-3 mm in diameter. The calcifications were located in the thickened gastric wall in all cases, and were seen in metastatic lesions such as lymph nodes and the liver in two cases. In 10 cases, some tumor portions showed lower attenuation number than that of the muscle on CT scans, and corresponded to mucin pool in tumor portions histologically. Twelve cases were in inoperable advanced stage.

MR imaging of hypertrophic cardiomyopathy

To assess the capability of magnetic resonance (MR) imaging to define the presence, distribution, and severity of the hypertrophic process, MR imaging was performed in 20 patients with hypertrophic cardiomyopathy and in five healthy volunteers. Among the 20 patients, 13 were classified as having asymmetric septal hypertrophy and seven as having apical hypertrophy. The mean myocardial thickness in the four-chamber view obtained in end diastole in asymmetric septal hypertrophy was 23.5 mm +/- 6.8 (mean +/- standard deviation) in the basal septum; the ratio of septal to posterolateral wall thickness was 2.05 +/- 0.44 (P < .05); those values were 10.4 mm +/- 2.7 and 1.01 +/- 0.19, respectively, in five healthy volunteers. The mean myocardial thickness in apical hypertrophy was 25.3 mm +/- 4.1 in the apex, and the ratio was 2.21 +/- 0.51 (P < .05); these values were 9.6 mm +/- 1.5 and 0.95 +/- 0.17, respectively, in five healthy volunteers. Three different subtypes of hypertrophic cardiomyopathy - resting obstructive (n = 5), latent obstructive (n = 3), and nonobstructive (n = 5) - were classified according to findings at catheterization in the 13 patients with asymmetric septal hypertrophy.

Infarction of the kidney: role of contrast enhanced MRI

Magnetic resonance imaging was performed on nine kidneys in six patients with renal infarction caused by renal arterial embolism secondary to cardiac valvular disease. The time interval between the onset of the symptoms attributable to renal infarction and the date of MRI was 2-23 days. On both T1- and T2-weighted images the signal intensity of the infarcted area was lower than that of the noninfarcted area in six kidneys and higher in three kidneys. Postcontrast T1-weighted images demonstrated the extent of the infarction except in the kidney in which the infarcted areas had high signal intensity on precontrast T1-weighted images.

Hypointense boundary layer between slow flow and mural thrombus on spin-echo MR

To evaluate the ability of spin-echo MRI to differentiate between slow flow and mural thrombus in aortic diseases, we reviewed the spin-echo MRI of 10 patients with intraaortic thrombus that had been documented by CT in 8 patients and aortography in 2 patients. Six patients had aortic aneurysms with mural thrombi, and four had aortic dissections with adherent mural thrombi within the false lumen. Five of seven gated oblique sagittal or coronal T1-weighted studies demonstrated hyperintense slow flow signal within the residual lumen. This hyperintense slow flow signal was accompanied by a parallel hypointense rim due to a boundary layer dephasing phenomenon. Eight axial T2-weighted MR studies demonstrated a hypointense zone due to fresh clot at the edge of a mural thrombus on even-echo images consistently. The hypointense boundary layer between slow flow and mural thrombus on either gated T1-weighted MRI or second-echo T2-weighted MRI not only predicted the presence of flow within the residual lumen but also clearly separated the area of slow flow from that of mural thrombus in 9 of 10 patients. Proper interpretation of spin-echo images may obviate the need for phase display imaging or gradient-echo imaging in differentiating between slow flow and mural thrombus.

Bronchial stenosis due to endobronchial tuberculosis: successful treatment with self-expanding metallic stent

Endobronchial tuberculosis is present in 10-40% of patients with active pulmonary tuberculosis, and more than 90% of the patients with endobronchial tuberculosis have some degree of bronchial stenosis. The primary treatment for tuberculous bronchial stenosis is antituberculous chemotherapy combined with steroids, but some patients do not respond well, and more aggressive treatment is needed to restore the patency of the involved bronchus. Balloon dilatation of tuberculous bronchial stenosis has been reported to be successful. However, in our experience, balloon dilatation of the stenotic segment has not significantly improved patients' clinical symptoms except in those with very short segmental stenosis. We describe a case of tuberculous bronchial stenosis that was successfully treated with Gianturco self-expanding metallic stents.

Direct invasion of urinary bladder from sigmoid colon cancer: CT findings

Radiological findings in three cases of sigmoid colon carcinoma invading the urinary bladder are reported. An irregular spiculated margin or nodular indentations in region of bladder dome were seen on intravenous urography. A soft tissue mass contiguous with an irregularly thickened urinary bladder wall and a circumferentially thickened sigmoid colon wall were demonstrated on CT and sonography and led to the correct diagnosis.

Retrieval of intravascular foreign bodies with the snare and catheter capture technique

The authors report two cases of retrieval of iatrogenically placed intravascular metallic foreign bodies: a guide wire in the abdominal aorta and a guide-wire fragment in the inferior vena cava. The foreign bodies were retrieved with use of a new approach described as the "snare and catheter capture technique." This technique is useful with guide wires that are too stiff to safely remove doubled over.

Therapeutic effect of transcatheter oily chemoembolization therapy for encapsulated nodular hepatocellular carcinoma: CT and pathologic findings

An emulsion of iodized oil and doxorubicin hydrochloride was intraarterially injected in 27 patients with encapsulated single nodular hepatocellular carcinoma (HCC). Computed tomography (CT) was performed 1-3 weeks after injection, and the lesions were resected 1-4 weeks thereafter. The percentages of tumor necrosis were evaluated in cut surfaces of resected specimens and were compared with the findings at iodized-oil CT. Six tumors with complete intratumor retention of iodized oil had 98% necrosis, and 21 tumors with incomplete retention had 64% necrosis. Two tumors with complete retention of iodized oil in the surrounding liver had 100% necrosis, while 16 tumors with partial retention and nine tumors without retention of iodized oil in surrounding liver had 74% and 62% necrosis, respectively. Complete retention of iodized oil in the tumor and surrounding liver demonstrated the best therapeutic effects. Evaluation of the pattern and distribution of iodized oil in the tumor and surrounding liver with iodized-oil CT is useful in the assessment of the therapeutic effects of transcatheter arterial embolization in encapsulated nodular HCCs.

[IL-2 potentiates the IL-3 production by ConA activated mouse splenic T cells]

In addition to the regulation of T cell growth, IL-2 exerts effects on the induction of certain lymphokines. We show here that IL-2 synergizes with 5 micrograms/ml of ConA to promote the production of IL-3 in mouse splenic T cell cultures. IL-3 was measured as CFU-GEMM-inducing activity on mouse bone marrow progenitor cells in the supernatant of the stimulated mouse splenic T cells (TCM). The resting T cells produced no CFU-GEMM-inducing activity, but could be induced to produce low level of CFU-GEMM-inducing activity in the presence of ConA. In vitro exposure to IL-2 markedly increased CFU-GEMM-inducing activity production (nearly up to 8-fold) by the ConA-activated T cells. Optimal stimulation was observed when 80 u/ml IL-2 was used for 48 h incubation. Anti-mouse IL-3 monoclonal antibody inhibited the CFU-GEMM inducing activity of TCM. Moreover, the TCM stimulated the proliferation of IL-3 dependent cell line FDC-P1. We also show that IL-2 and ConA-treated T cells expressed high level of IL-3 mRNA through dot blot analysis. These results confirmed the nature of CFU-GEMM-inducing activity of TCM as IL-3. The capacity of IL-2 to promote the production of IL-3 may represent an important mechanism by which it mediate the communication between the immune and hematopoietic systems.

Reducing inositol lipid hydrolysis, Ins(1,4,5)P3 receptor availability, or Ca2+ gradients lengthens the duration of the cell cycle in Xenopus laevis blastomeres

We have microinjected a mAb specifically directed to phosphatidylinositol 4,5-bisphosphate (PIP2) into one blastomere of two-cell stage Xenopus laevis embryos. This antibody binds to endogenous PIP2 and reduces its rate of hydrolysis by phospholipase C. Antibody-injected blastomeres undergo partial or complete arrest of the cell cycle whereas the uninjected sister blastomeres divided normally. Since PIP2 hydrolysis normally produces diacylglycerol (DG) and inositol 1,4,5-triphosphate (Ins[1,4,5]P3), we attempted to measure changes in the levels of DG following stimulation of PIP2 hydrolysis in antibody-injected oocytes. The total amount of DG in antibody-injected oocytes was significantly reduced compared to that of water-injected ones following stimulation by either acetylcholine or progesterone indicating that the antibody does indeed suppress PIP2 hydrolysis. We also found that the PIP2 antibodies greatly reduced the amount of intracellular Ca2+ released in the egg cortex during egg activation. As an indirect test for Ins(1,4,5)P3 involvement in the cell cycle we injected heparin which competes with Ins(1,4,5)P3 for binding to its receptor, and thus inhibits Ins(1,4,5)P3-induced Ca2+ release. Microinjection of heparin into one blastomere of the two-cell stage embryo caused partial or complete arrest of the cell cycle depending upon the concentration of heparin injected. We further investigated the effect of reducing any [Ca2+]i gradients by microinjecting dibromo-BAPTA into the blastomere. Dibromo-BAPTA injection completely blocked mitotic cell division when a final concentration of 1.5 mM was used. These results suggest that PIP2 turnover as well as second messenger activity influence cell cycle duration during embryonic cell division in frogs.